The Hollows is a Hazard Zone in City of Heroes. A hero needs to be at least level 5 to enter. The Hollows was added as a zone in Issue 2.
This hazard zone is an outlet of Eastgate Bay in Paragon City. After the Rikti War, this section of the city was sealed off to normal traffic, which made it a haven for criminals such as the Trolls , Hellions , Skulls , The Lost and the Outcasts. In recent months, the city has granted limited access to the zone for heroes of the appropriate security level (5 and up) in an effort to retake it from the villain groups that now inhabit it. The deeper into the Hollows you go, the tougher the gangs can be, and the extensive cave networks in the area are rumored to lead to an underground city controlled by the Circle of Thorns. Recent reports indicate an increasing number of Coralax now inhabit the Red River area.
These woods have cropped up at an alarming rate since the Hollowing. Many believe the dramatic growth rate of the trees is due to the area being saturated with mystical residue from the Circle's spells.